The present invention relates to an oil feeder for a machine tool, and more particularly to a method of and an apparatus for feeding cutting oil to a turret punch press.
One well known type of a turret punch press 1 is shown in FIG. 3. This turret punch press 1 comprises an upper rotatable turret 2, a sleeve 5 slidably received in the upper rotatable turret 2, a punch body 4 slidably received in the sleeve 5 and having an upper tool 3 on its lower end which is slidably extendable through a bottom end of the sleeve 5, a lower rotatable turret 6, and a cylindrical die 11 fastened to the lower turret 6 and comprising a lower tool 7. A material A is interposed between the upper and lower turrets 2 and 6 and superposed on the upper face of the lower tool 7. A flange 8 provided on the upper end of the sleeve 5 determines the extent to which the sleeve 5 can be vertically lowered. A compression spring 10 is interposed between the flange 8 and another flange 9 provided on the upper end of the punch body 4, such that the punch body 4 is biased upwardly. In order to effect punching, a striking force is exerted on the upper end face of the punch body 4 by a hammer 12 disposed over the punch body 4, such that the punch body 4 is vertically lowered to such an extent that the upper tool 3 fits in the lower tool 7.
In a turret punch press of this type, the sleeve 5 is in sliding contact with the punch body 4, and the upper turret 2 is in sliding contact with the sleeve 5. Thus, it is conventionally considered necessary to periodically manually feed lubricating oil between these contact surfaces. In addition, it has been necessary to provide cutting oil to the upper tool 3 and the lower tool 7, and in attempting to do so, many difficulties have been encountered. In order to prevent these tools from seizing up on each other, it is most common to apply cutting oil to the surfaces of material A.
In order to feed the lubricating oil more efficiently, it is also common to connect a pressurized air supply source 13 and a pressurized oil supply source 14 to the hammer 12 by means of an oil pipe 15 as shown in FIG. 3. The punch body 4 is provided with a main oil passage 16 and a branch oil passage 17. As can be seen in FIG. 3 the passages 16 and 17 are disposed such that they are effective to feed lubricating oil to the upper tool 3 and the space between the punch body 4 and the sleeve 5. Furthermore, the sleeve 5 is formed with an oil passage 18 extending from the space between the punch body 4 and the sleeve 5 to the space between the sleeve 5 and the upper turret 2 so as to further supply lubricating oil to the space between the sleeve 5 and the upper turret 2.
Although hand lubrication has the advantage of being relatively inexpensive in cost, the disadvantage of hand lubrication is that the labor required therefor is not negligible. Furthermore, one is occasionally so absentminded that he fails to carry out hand lubrication. The automatic lubrication described in the preceding paragraph also has its merits and demerits. Although the automatic lubrication serves to improve the working efficiency, the alterations required to adapt the apparatus for automatic lubrication involve high installation costs. Another disadvantage to the automatic lubrication is that it is impossible to feed both lubricating oil and cutting oil to the proper places at the same time. Still another disadvantage to automatic lubrication is that the products and the equipment are fouled and the work environment is spoiled by pressurized oil splashing out of the apparatus.
Yet still another disadvantage to automatic lubrication is that it is difficult to set the rate of oil flow and the timing of oil outflow in a CAM system, such that the oil feed cannot be smoothly and precisely effected.
Thus, none of the prior art apparatuses is capable of satisfactorily feeding cutting oil to the upper tool and the lower tool. In order to prevent these tools from seizing up on each other, it is common to either make do with lubricating oil in place of cutting oil or to apply cutting oil to the surfaces of the material so that at least a small portion of the cutting oil may be supplied to the cut edges of the material.